WASHINGTON — The U.S. Defense Department has changed course in its plan to defend Europe and deployed forces from ballistic missile threats and will now pursue a more mobile and flexible architecture based on the Raytheon-built Standard Missile (SM)-3 interceptor, Secretary of Defense Robert Gates said Sept. 17.

The new approach is based on revised U.S. intelligence estimates that indicate the Iranian ICBM threat has developed less quickly than anticipated, and European allies and U.S. forces deployed on the continent are more likely to face attacks of many more short- and intermediate-range ballistic missiles from Iran, Gates said during a media briefing at the Pentagon. U.S. missile defense technology has also advanced rapidly in the last several years and the ability to counter short- and medium-range missiles has been validated in testing, he said.

“Those who say we are scrapping missile defense in Europe are either misinformed or misrepresenting the reality of what we are doing,” Gates said. “The security of Europe has been a vital concern for my entire career.”

The new plan is a revision to the program recommended by Gates and signed off on by then-U.S. President George W. Bush in 2006. That plan would have placed 10 long-range Ground-Based Interceptors in Poland based on the interceptors the United States has deployed in Alaska and California. A fixed radar site was to be placed in the Czech Republic. Polish and Czech leaders signed off on the plan despite objections and threats from Russia, but neither the Polish nor Czech parliaments had given their approval.

Now, the United States will seek to station U.S. Navy Aegis ships equipped with SM-3 interceptors built by Raytheon Missile Systems of Tucson, Ariz., in the Mediterranean and North seas starting in 2011, Marine Corps Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, said at the briefing. Cartwright said that by 2015, a land-based SM-3 based on the new Block 1B variant could be placed in Poland, the Czech Republic or other locations in Europe.

The SM-3-based system will rely on directional X-band radars that would be pointed south toward Iran, as opposed to the omni-directional Czech radar that would have been capable of peering deep into Russian territory, Cartwright said. The radars likely will be placed in the Caucases, between Europe, Asia and the Missile East, he said. A new set of airborne and space-based sensors will also be developed to support the system.

Toward the end of the decade, the system will evolve for defense against ICBMs, Cartwright said. The United States is co-developing with Japan the larger and more capable SM-3 Block 2A missile, and an even more energetic Block 2B missile will follow. The new missiles could be deployed in 2018 and 2020, respectively, he said. However, the United States will continue to develop and test the two-stage version of the Ground-Based Interceptor that originally was planned for deployment in Europe as a hedge against development problems with the larger SM-3 interceptors, he said.

The new course charted for European missile defense is not an attempt to allay Russian concerns, Gates said. But no longer can the Russians credibly claim that the U.S. system could be outfitted with nuclear weapons, and no longer will a radar scan Russian territory, he said.

“The decisions on this were driven almost exclusively by the change in intelligence and better technology,” Gates said. “I think that the Russians are not going to be pleased we are continuing with missile defense in Europe.”

Missile defense advocates in Congress voiced their displeasure with the new plan almost immediately.

“The [Obama] Administration apparently has decided to empower Russia and Iran at the expense of the national security interests of the United States and our allies in Europe,” U.S. Rep. Howard McKeon (R-Calif.), ranking member of the House Armed Services Committee, said in a statement. “Just this past April while in Prague, the President reiterated his support for U.S. missile defenses in Europe as long as missile threats persist.

“The Administration now claims that the threat from Iran, specifically, has been ‘downgraded.’ The timing of this intelligence assessment is interesting. We hope, and will request, that the Administration appear before the House Armed Services Committee to explain the rationale behind this decision, complete with the requisite intelligence estimates.”

McKeon noted that the United States did not get any security concessions from Russia in return for its new plan. “It’s troubling that we would negotiate against ourselves on something as important as the security of the United States and our allies,” he said.

U.S. Sen. Carl Levin (D-Mich.), chairman of the Senate Armed Services Committee, applauded the decision for focusing on the most relevant threat.

“President Obama has made a sound choice that will improve our security,” Levin said in a Sept. 17 press release. “The president’s decision focuses on fielding effective capabilities to defend our forward deployed force and allies in Europe against the real and existing missile threat from Iran, which consists of short- and medium-range missiles, rather than only against a potential future long-range threat. Iran already has many hundreds of short- and medium-range missiles, and has been adding more, but will not have long-range missiles for years to come.”